Prohibited concomitant therapy Concomitant use of sargramostim, other anti-cancer therapies, including thalidomide, or other investigational agents is not permitted while subjects are receiving study drug of the study. The need for radiation therapy is considered to be a treatment failure. However, an exception (that is patients allowed to remain in the treatment phase of the study) is made for radiation therapy to a pathological fracture site to enhance bone healing or to treat post-fracture pain that is refractory to narcotic analgesics because pathologic bone fractures do not by themselves fulfill a criterion for disease progression End of study treatment. Patients may continue study treatment until Progression develops (last study drug intake of pomalidomide-dexamethasone regimen) at which time they will complete a Treatment Discontinuation visit as outlined in Table 2.